


Room For One More

by Dragonmaster



Series: Beautiful Together [2]
Category: Transformers: Prime, Undertale (Video Game)
Genre: Crack Crossover, Crossover, Crossover Pairings, M/M, Mettaton Gets a Harem, Plot What Plot/Porn Without Plot, Sticky Sexual Interfacing, Threesome, What Have I Done
Language: English
Status: Completed
Published: 2017-01-13
Updated: 2017-01-13
Packaged: 2018-09-17 04:41:19
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 7,160
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9304709
Author URL: https://archiveofourown.org/users/Dragonmaster/pseuds/Dragonmaster
Summary: Sequel to "Beautiful Together."  Knock Out has been missing for months, and Breakdown descends into the Underground to find him.  When he finds out just what -- or who -- his bondmate has been doing, things get interesting FAST.





	

**Author's Note:**

> Welp, "Beautiful Together" wasn't a one-shot after all. It's highly recommended you read that one first, or you might be confused as to why we have transforming robots romping around the Underground.
> 
> No real spoilers save Mettaton's EX form -- and yes, the robots are all hermaphrodites in this 'verse. Enjoy it. ;)
> 
> STILL NOT SORRY

“Oh my… two of them in so short a time! The surface world seems to have changed greatly since we’ve been sealed down here…”

Breakdown groaned and onlined his optic, shutters squinted as he tried to focus his vision. He’d never heard that voice before -- it was female, but sounded nothing like Airachnid or whatever that Autobot femme of Prime’s was named. And it lacked the metallic undertone typical of his kind, but sounded softer, with a rippling accent to the vowels. Some sort of organic, then…

“Greetings, Iron One,” the voice went on. “I am Toriel, the caretaker of the Ruins. Are you hurt? I’m not sure if beings of metal can take harm from a fall, but then, it WAS quite a fall...”

He pushed himself to his feet, shaking his chassis to shed the flowers that had gotten caught in his armor. His fall had taken him underground -- evidently he’d managed to drive over the crumbling roof of a tunnel or cavern and it had collapsed on him. Frag it all to the Pit… this search for Knock Out was going to get him killed. When he found the red mech he was going to give him a piece of his CPU. After making sure he was all right, of course…

The speaker stood just to his right, eyeing him with a friendly concern. She definitely wasn’t Cybertronian, but she didn’t match up with the native organics of this dirtball planet either. Last time he checked, humans didn’t have white fur, floppy ears, or horns, let alone all three. She wore a white-sleeved violet robe, and both her hands and her bare feet looked more like paws than actual hands.

“Can you not speak?” she asked, frowning.

“Frag yes, I can,” he growled, digging a clump of dirt out of a side seam. “Just kind of hard to have a conversation when you’ve just come back online after being knocked out. Give a mech a minute, will you?”

“My apologies,” Toriel replied. “I have only encountered another of your kind once, and he started talking the moment I came across him. Although he did not stick around for much conversation… simply said something about his finish and pushed by me to leave. Impatient, he was…”

Breakdown paused in the act of picking the last of the dirt from his joints. That was the second time she’d mentioned another Cybertronian coming down here. It had to be… “Red mech? Shorter and skinnier than me? Shiny and fussy about his looks?”

“That would be him. A friend of yours?”

Breakdown’s spark flared with a rush of triumph. Knock Out was here… this made traipsing all over a mountainside and falling into a tunnel worth it! Well, somewhat -- he was still going to tell the medic off for getting himself lost and bringing Megatron’s wrath down on them both when this was all over. But he had been missing for months now, and though Breakdown would never admit it, he had been getting terribly worried. He had lost too much to this war… he wouldn’t also lose the mech he had gotten close to after so many vorns.

“You could say that,” he told her. “Where is he?”

“As I said, he left pretty quickly.” She motioned for him to follow her, deeper into a violet-tinted set of ruins just ahead. “I would wager he’s still somewhere in the Underground, however. That is, if Asgore and his guards haven’t caught up with him yet…” She frowned, a troubled expression marring her gentle features, but Breakdown hardly noticed.

“Ma’am, I need to find him,” he insisted. “Preferably in one piece. Can you take me to him?”

“Are you certain?” Her frown deepened. “It’s dangerous beyond the Ruins, Iron One. There are any number of monsters who could do you harm…”

“I’ll risk it,” he retorted. “Just take me to him.”

“You could always stay here and wait for him to come back. There’s the possibility that he will return the way he came and seek an exit that way…”

“Lady!” he snapped. “Stop it with the distractions and either lead me to Knock Out or let me by! I ain’t got an excuse to squash you like a bug yet, but don’t give me one!” He wasn’t exactly sure how the squashing would work when she was his size -- had he shrunk somehow in coming down here? -- but at the moment he was too keyed up with frustration and worry to care.

Her eyes met his optic, and sudden understanding lit her face. “Oh! I see… that’s how it is.” Her features softened, and she rested a paw on his arm. “I can take you to the exit of the Ruins, but that’s as far as I can go. But if your friend had sense, he stayed on the path and made for Snowdin first thing. With any luck you will find him there.”

Breakdown snorted. “Finally.” He brushed the last of the dirt and crushed vegetation from his armor. “Lead the way, lady.”

“Toriel,” she corrected, and motioned for him to follow her. She wore a curious smile now -- knowing and amused. “Odd… I never would have thought a machine to be capable of love. But even here in the Ruins, I find myself constantly surprised.”

Breakdown snorted again. “Not a machine. Cybertronian -- autonomous robotic life form. But I ain’t got time to give you a lesson on my kind. I gotta find Knock Out and get us both the slag out of here.”

“You may find it harder to leave here than you think,” Toriel replied, a hint of sadness in her voice. “But you are welcome to try. Perhaps a Cyber… Cytro… a robotic life form will have more luck than a human or monster. Come… let’s get you out of here so you can find your friend in time.”

Breakdown nodded and mumbled a thank-you as he strode after the white-furred creature, spark buzzing with a heady mix of relief and worry. Knock Out was here… but was he safe? This place was already proving to be weird, and if Toriel was right it was dangerous as well. And Knock Out had a knack for landing himself in trouble. What kind of enemies had he made in a place like this? What sort of dangerous and horrifying situation had he managed to work himself into this time?

***

“Mmmm, yes… a little higher… there, perfect.” Knock Out gave a hum of pleasure and let his optics roll back a little in bliss. “You’re fantastic at this.”

The cat-like orange monster -- Knock Out had no idea what his real name was and refused to call him by that ridiculous Burgerpants moniker Mettaton favored -- just huffed and set the buffer aside. “When’s the boss going to hire someone else to do this? Seriously, polishing his new boyfriend is not in my job description.”

“I wouldn’t go so far as to say I’m a boyfriend,” Knock Out purred. “More of a guest with benefits. Do the shoulders a little more, will you?”

Burgerpants rolled his eyes but applied the buffer again. “I don’t get paid enough for this.”

The door to the lavish penthouse suite opened, and a tiny being that looked as if someone had folded him out of paper origami-style poked his head in. “Mettaton’s just finished an episode of his show. He’s on his way back in and wishes to know if you’re presentable, sir.”

“Just a few more minutes and I will be.” He reached for a dish of gold coins on the nightstand and flipped one toward the being. “Thank you, good sir.”

The creature caught the coin and gave a little bow before ducking out.

“Sure, the bellboy gets a tip.” Burgerpants turned off the buffer and began packing it up. “What am I, chopped liver?”

“Come now, I’m not an unappreciative customer.” Knock Out rolled over onto his back and arranged his limbs in his best pose, smirking at the cat. “I’d be perfectly happy to… thank you… for your services. I’ve never interfaced with an organic before, but it could be interesting.” He put on his most seductive smile. “I’ve heard some of you have kinky but fascinating tastes.”

Burgerpants looked like he wanted to lose his lunch right there. “Ugh… you’re not my type.” And he hurried out of the suite.

Knock Out laughed leisurely and rose from the bed. It was more luxurious than anything he’d ever had in his life -- soft and silky, yet sturdy enough that Megatron could have fragged Starscream senseless atop it without so much as tearing the sheets. Evidently it had been built with even the biggest and heaviest monsters in mind. The rest of his five-room suite was much the same way -- beautiful and luxurious, but strongly built.

He had been living here for several months, mainly resting and reading and refueling while Mettaton went about his business of running his hotel and keeping the Underground supplied with entertainment and music. The black-and-magenta mech had assured him that he was perfectly safe here, and only asked in return that he provide a little relaxation and pleasure in the evenings when Mettaton returned to the hotel. A request that Knock Out was all too happy to oblige -- he enjoyed their sessions every bit as much as Mettaton did.

He had no intention of staying here forever -- he itched to feel open road on his tires and wind on his curves again, and some part of him knew that the longer he stayed down here enjoying his unplanned vacation, the angrier his superiors would be when he finally returned to the Nemesis. But escape from this strange world could come later. For now, he intended to enjoy his time AWOL as long as he could. And besides, who could say no when said “vacation” came with one of the most divine pieces of metal he had ever had the privilege to bed?

 _I only wish Breakdown were here to share this,_ he mused, taking another can of some sort of alcoholic drink from the mini-bar -- shockingly, the food and drink here was easily processed by Cybertronian systems, as it converted directly to energy without producing waste. _I’m sure he’s worried himself sick by now. And I know for a fact he would like it down here…_

The door swung open, revealing Mettaton in his blocky calculator form. “Darling, I’m home!”

Knock Out set his drink down and gave him a mock pout. “Oh, MUST you make your entrance in THAT body? It’s so blocky and bland. No sense of style whatsoever.”

“Darling, you wound me!” Mettaton pressed a hand to his chassis. “My audience loves this form, and I must keep my adoring fans happy. But I promise you, when I debut my true form for the cameras, I will never return to this body.” He wheeled further into the room. “And how was your day?”

“Lazy and relaxing.” Knock Out sat down on the bed again. “Are the King’s guards still looking for me? As much as I’m enjoying the accommodations, I do hate being cooped up for too long.”

“According to the news reports I just gave out, the Royal Guard will recall the search parties in forty-eight hours,” Mettaton replied. “It did pain me so to report my failure to destroy you -- I do like to consider myself the best in all I do -- but I really didn’t want to lose a playmate so soon.” He chuckled and scooted to the side of the bed. “Once Asgore gives up the search, you’re free to emerge from hiding.”

“I look forward to it.” He smiled and ran a claw down Mettaton’s arm. “Do turn around, darling… I’ll help you out of that dreary work uniform.”

“You’re too kind, gorgeous.” Mettaton turned in place, and Knock Out reached down to slide the switch on his back to the side. A grin of pleasure stretched his lip plates as the other mech’s brick-like chassis opened like a blooming flower, reconfiguring itself into the devastatingly beautiful EX form he had grown to appreciate so much.

“Long day?” Knock Out asked, pulling him into his lap. 

“Always, darling.” Mettaton rearranged himself until he was straddling the scarlet mech’s thighs, resting his hands on the smooth metal of his chest. “It’s such a hard task, keeping the Underground entertained and informed all day, every day. But it’s so worth it.” He cupped Knock Out’s face in his hands. “You’re such a fine specimen, gorgeous… I do wish you would reconsider my offer to stay on as my co-host. You’d send my ratings through the stratosphere!”

“Mmmm… tempting.” Knock Out turned his head just enough to kiss Mettaton’s hand, then nibbled playfully at his fingers. “Alas, I must decline again. I have places to be. But I would be delighted to come down and visit from time to time… or even take you with me. I guarantee you would be adored on the surface.”

“Ooooh, you promise?” Mettaton let the fingers of his other hand drift downward, tweaking sensitive wires in Knock Out’s neck until the crimson mech was quivering in delight. “Sadly, I am needed here. What would the Underground do without its brightest star?”

“Pity. Then I’ll just have to visit frequently.” He placed his clawed hands on Mettaton’s delicious aft and thrust his hips gently against him, making him arch his back and groan in pleasure. “Mmmm… I could never get tired of the sounds you make, beautiful.”

“Oh really? Then I’ll give you a concert you’ll never forget.” Mettaton leaned in to capture Knock Out’s mouth in his, biting at his lip plates before kissing down his throat, his chest…

A knock on the door interrupted their interlude, and Mettaton let out a string of soft curses before turning to face the door. “I provide guests with ‘Do Not Disturb’ signs for a reason!”

“I’m terribly sorry, Mettaton sir, but there’s a disturbance in the lobby.” The origami-looking monster opened the door a crack and peeked in, looking entirely unconcerned with the fact that his boss was romantically entangled with a “killer robot” -- from what Knock Out understood, all the employees were keeping silent on his presence here thanks to a generous pay raise. “Another of those robots is just outside the hotel, and it appears to be on the verge of going on a rampage.”

“Oh, bother.” Mettaton climbed down from Knock Out’s lap. “Your friends don’t like to play nice, it seems. Think you can talk him down?”

Knock Out sighed softly. He had hoped to avoid discovery for a little longer. “It depends on which one it is. What does he look like?” It had better not be Megatron or Dreadwing… though if it was an Autobot at least he could shoot them and prolong his vacation a little longer, and maybe even prove himself a hero to the monsters…

“Big, bulky, blue, a patch over one eye,” the bellhop provided.

Mettaton chuckled. “Are you sure it’s not Undyne you’re talking about?” His gaze moved to Knock Out, and his laughter faded at the sight of his stunned expression. “Darling? Someone you know?”

Knock Out’s spark blazed in his chest, sending a thrill of wonder and excitement through him. Big, bulky, and blue could have been Dreadwing, but only one mech he knew of had an optic patch… could it be?

He rose from the bed and ran out of the room, down the corridor, and into the resort’s lobby. Several of the hotel’s employees -- the origami creature, a man composed of green slime, a fat fish-monster, a blue-skinned being with a giant hand for a head -- were gaping at the blocky blue mech who stood just before the hotel’s fountain, hammer raised, golden optic glinting with anger. The slime-man held a mop before him like a spear, as if he intended to fight the mech, while the hand-headed being had one hand on the phone, no doubt on the verge of calling for help.

“Where is he?” Breakdown snarled. “I know he’s here -- the stupid skeleton told me I might find him here!”

“Sans is full of it!” Burgerpants shouted from the relative safety of the fast-food restaurant just off the lobby. “Just go home and leave us alone!”

“Hand him over and no one gets hurt!” Breakdown thundered. “I mean it!”

A soft electronic whistle droned at Knock Out’s side, and he turned to see Mettaton, back in computer form, staring at the blue mech. Even in this form, he couldn’t disguise his awe and admiration.

“He’s gorgeous,” Mettaton murmured. “Not that you aren’t magnificent, darling, but…”

“Oh, no offense taken at all,” Knock Out replied with a grin. “He’s very handsome… especially when he’s in a fighting mood. But let’s not have him wreck your lovely resort too much, shall we?”

“I would appreciate that.” Mettaton scooted over to the employee at the front desk to defuse the situation, while Knock Out strode up to Breakdown, hands raised.

“Breakdown, do put down the hammer,” he urged him. “I just had a buffing done and don’t want dents in my body work.”

Breakdown whirled… and his jaw dropped. “Knock Out?”

“Glad to see you still remember me.” He smirked a little. “I was beginning to think everyone had forgotten me. Do shut your mouth, darling. That expression isn’t very becoming.”

Breakdown shook his arm, his hammer retracting back into his arm. In three strides he had crossed the distance between himself and the scarlet medic, sweeping him up in his arms and holding him tightly to his chest.

“Knock Out, you had me scared to death!” he exclaimed, laughing with relief. “When you went missing, Megatron decided you must have defected to the Autobots… but I couldn’t believe it. I had to find you, even if it meant disobeying him…”

“Aw, darling, you do care.” He chuckled and planted a kiss on Breakdown’s lips… and gasped in surprise when the blue mech responded in kind, and with far more passion than he’d expected. As experienced as Mettaton’s kisses were, there was something exciting and erotic at the power and unrestrained passion in Breakdown’s kiss…

A robotic cough broke into his reverie, and he turned to find the occupants of the lobby staring at them -- Mettaton with a blush so luminescent it colored his screen a vivid pink, the employees with varying degrees of amusement and disgust.

“I’m gonna be sick,” Burgerpants groaned.

“Oh, hush, you,” the slimy janitor huffed, lowering his mop. “It’s not any less gross than those burgers you cook. Way less so, actually…”

Mettaton glided forward at that moment, and looped his arms through both Breakdown’s and Knock Out’s. “Your suite, Knock Out. Now. I MUST get acquainted with your friend here.”

Breakdown’s optic rebooted in surprise. “Who’s this?”

“A friend,” Knock Out replied. “Trust me, you will love him.”

***

Mettaton wouldn’t lie -- when he’d first seen that passionate kiss Knock Out and Breakdown had shared upon their reunion, the first emotion to flare through his soul had been jealousy. How dare this interloper just swoop on in and snatch away his new lover? Never mind that the two of them had obviously been close before Knock Out had fallen into the Underground; in Mettaton’s mind, Knock Out was his, and he hated to see him stolen from him.

But he had reined in his envy enough to listen as Breakdown had explained what was going on above the surface. And exciting news it was -- a secret robot war being waged right under humankind’s collective nose! Some small part of him fretted that said war would result in the destruction of the humans, whom he couldn’t help but admire, but the rest of him reasoned that a surface world ruled by robots wouldn’t be so bad. Especially if most or even just some of them were as delectable as Knock Out…

Knock Out folded his arms and gave an exaggerated pout as Breakdown finished his summation of the events on the surface. “Desertion? Defection? Oh, please, does Megatron really have SO little faith in me? I might be vain, self-centered, and a perfectionist -- who wouldn’t be in my situation -- but I’d sooner go without wax than wear a tacky Autobot sigil.”

Breakdown shrugged. “You kind of vanished without much explanation. I guess Megatron assumes all his troops are as disloyal as Starscream unless they prove otherwise.” He shifted, trying to get comfortable in a chair that was far too small for his frame. “I knew otherwise, though -- like you said, you’re not just going to up and join the Autobots for no good reason. So I came here to look for you. I must’ve fallen into the same pit you did, though, and from there the white-furred lady and the skeleton pointed the way here.”

Knock Out cocked his head. “I remember the lady… though I was in too much of a hurry to say much to her. I can’t say I met a skeleton, however. Most of the creatures I encountered turned and ran the moment I saw them.” He reached out to pat Mettaton’s arm. “With one exception, of course.”

Mettaton felt a thrill of pleasure at the touch. “Oh darling, how could I run from such a magnificent display of metal such as you?”

Breakdown frowned. “Who’s this?”

“Oh dear me, where are my manners?” Knock Out chuckled and gestured toward Mettaton. “May I introduce Mettaton, owner and general manager of MTT Resort and of the MTT broadcasting station, actor, singer, designer, artist, and all-around entertainer of the Underground. Quite a mech of many talents… MANY talents.” He said that last with a lascivious wink.

The blue mech stared at Mettaton as if trying to puzzle out what kind of creature he was. “He ain’t like any robot I’ve ever seen.”

“Oh, trust me, dearest, he’s gorgeous.” Knock Out let his claws dance up Mettaton’s arm, making him give a little shiver. “Not to mention fantastic in the berth.”

“Um…” If Breakdown’s face contorted in confusion any more, he was going to crack something. “No offense, Metta sir, but… Knock Out, did you head your head on the way down? Sounds like you’ve got a screw loose in your CPU.”

Mettaton drew himself up straight, his lingering jealousy quickly morphing into anger. “Why, I never!”

“Easy, darling,” Knock Out urged, gripping his arm. “Breakdown just hasn’t seen your best side yet. And really, Breaky, we can’t judge every mech by his alt mode, can we?”

“That’s his alt mode?” Breakdown’s single optic -- he really did look rakishly handsome with that eyepatch -- lit up in understanding. “Oohhhhhhhhhhh… all right, so he turns into some kind of calculator with arms. Never seen an alt like that. Sorry, thought that was some kinda weird root mode.” He looked back to Knock Out. “So what’s his primary mode look like?”

Mettaton’s anger died down a little at that. Well, as delightful as some monsters found his rectangular mode, he had to admit it paled in comparison to his EX form. “Knock Out, my beauty, a little help?”

Knock Out bent down and flipped his switch… and Breakdown’s face went blank with shock as he shifted. He tossed his head, letting his glossy black hair flip back and gleam in the lamplight, and offered the blue mech his most seductive smile.

“I take it back,” Breakdown murmured. “An’ I’m sorry for everything I said earlier. Holy frag…”

“We’ve been doing a great deal of that lately,” Knock Out chuckled. “Isn’t he magnificent? Not as heavy-duty and well-built as you, but stunning nonetheless.”

Well, in the face of that admiring expression and Knock Out’s compliments, how could he remain angry? Mettaton relaxed, taking a moment to look Breakdown over and fully appreciate this newcomer. He was nowhere near as sleek as Knock Out, but he was truly handsome in his own way -- powerfully built, a deep and vibrant blue accentuated with silver and red in just the right places, and with strong and massive hands that nonetheless moved with a careful grace, as if he were fully aware of his own great strength and took pains to control it. And there was something about the way his mouth curved when he grinned… a mouth that just an hour or two ago he had seen working quite expertly on Knock Out’s own lips…

“Um… Knock Out, he’s staring at me like he wants to eat me.”

Knock Out burst out laughing. “Oh, Breaky, I’d call that a compliment.”

Mettaton flushed slightly, but didn’t let his embarrassment creep into his voice. “Darling, as delectable as you look, how can I not want to taste?” His gaze moved to Knock Out. “That is, if I have your permission.”

“Mettaton, darling, you don’t need my permission,” the red mech replied, chuckling. “You just need his.”

Breakdown’s optic flashed, and he grinned like a child who’d just received the best present of his life. “You sure you’re okay with this, Knock Out?”

Knock Out chuckled. “Breaky, dearest… we’ve always agreed that we’ll belong to each other no matter who we interface with. If you want to spend a little time with him, I won’t object in the slightest.”

Mettaton felt his systems begin to flutter in anticipation. Were they saying…

“Mettaton,” said Breakdown, his voice softening to a register that sounded downright seductive to his audials, “I owe you thanks for taking care of Knock Out while he’s been down here. Instead of just saying it, though… I wanna show it.”

Mettaton nearly swooned on the spot, keeping himself on his feet only through sheer willpower. “And just how do you propose to do that?”

Breakdown reached out, grasped Mettaton around the waist, and pulled him close. He gasped and pressed his hands to the blue mech’s chest -- not to push him away, but merely to steady himself. By Asgore’s horns, the thrum of his engine send the most delicious shivers through his chassis…

“Let me show you,” Breakdown growled, voice dropping to an erotic rumble to match his engine, and he pressed his mouth to Mettaton’s.

 _Oh. My. Stars._ He was melting, he was sure of it. He could feel his entire chassis turning to jelly in this mech’s hands as he kissed him, gently but deeply, one hand pressed to the small of his back and the other reaching up to toy with his hair. He had been fantasizing about this almost since seeing him kiss Knock Out in the lobby, but THIS… it was far better than simple fantasy.

Metallic feet clicked on the marble floor of the suite, and Mettaton gasped into Breakdown’s mouth as delicate claws began to fondle his sides and hips. “Mmmm… I don’t mind sharing you with Breakdown, Mettaton… but I’m wondering now if Breakdown will share you with me. I can think of all sorts of things we can get up to tonight…”

Breakdown broke the kiss and laughed. “Someone’s greedy. You’ve gotten him to yourself for months.” But he made a little gesture with his head, indicating Knock Out could join in.

Mettaton hissed in delight as Knock Out’s smooth-plated chassis pressed up behind him, his mouth nibbling gently at the wiring in his neck. One of these splendid mechs’ company for the night would have been exquisite enough, but both… it was a dream come true. 

Then Breakdown’s mouth pressed back down on his, obliterating all thought. He groaned deeply and surrendered to both mechs, simply reveling in the larger one’s powerful hands on his hips and the smaller one’s claws exploring gaps in his plating. His hips jerked erratically against Breakdown’s pelvic armor, heat blooming within his own panel as Knock Out drove him wild with those magnificent hands and lips.

Breakdown broke off the kiss with a primal groan of his own. “Frag… keep that up and I won’t be able to control myself.”

Mettaton chuckled and let his hands explore Breakdown’s chest, smirking as the larger mech jerked and shuddered whenever he discovered a sensitive spot. “Maybe I want you to lose control.”

“Don’t wanna hurt you,” Breakdown groaned, but he made no move to push Mettaton away. If anything, he just clutched him closer, his own hips bucking beneath the entertainment bot’s. 

“He’s far sturdier than he looks,” Knock Out assured him. “Here, try this… it’s one of his most sensitive spots, aside from the obvious.”

“What-” Mettaton began, only for his words to be choked off as Breakdown lightly pressed a thumb over the heart-shaped plate on his abdomen… the one that protected his soul. A jolt of pleasure so strong it nearly blinded him shot from his throat to his groin. A wild, almost auto-tuned cry filled the air, and it took him a moment to realize it was coming from him.

“Oooh Primus.” Breakdown wore an expression of wonder and delight as he continued to fondle and caress the body in his lap, making Mettaton squirm and groan. “He makes the best noises.”

“Better than mine?” Knock Out mock-pouted, then grinned and turned Mettaton’s head enough to lock lip plates with him. Mettaton could only moan helplessly as the red mech plundered his mouth and the blue mech continued his exploration of his body. 

“Who gets him first?” Breakdown rumbled, lightly kneading Mettaton’s thighs.

“Who says we have to take turns?” Knock Out chuckled. “You get his valve… I’ll get his spike. Fair?”

Mettaton broke off the kiss, gasping for air to cool his internals. “D-Darling,” he replied, managing to keep his stammer to a minimum. “I’d be delighted to give you my spike at any other time… but tonight, I want BOTH your spikes.”

Knock Out arched an optic ridge -- gods, only he could make a look of skepticism look sexy. “I’m not sure both our spikes would fit inside you, Mettaton dearest.”

“They can… and I know just the technique to ensure it.” And to emphasize his point, he let his glossa slide out of his mouth and trace his lips in a gesture calculated to make anyone with even the barest sliver of a sex drive dissolve into a puddle.

“Oh!” Knock Out’s optics flared, and he gave a throaty chuckle. “I love how you think, darling. Breakdown, we’re taking him from either end.”

“I like that position,” Breakdown laughed. “You ready, Metta?”

“Darling… I’ve been ready from the moment you first kissed me.” Mettaton winked and slid out of Breakdown’s lap, arranging himself on all fours on the room’s faux-fur rug. He looked over his shoulder at Breakdown and winked, waggling his hips from side to side in an invitation one would have to be both blind and completely neutered to mistake.

Breakdown’s response was both immediate and impressive -- a panel on his pelvic armor slid aside, freeing a truly impressive spike. It wasn’t as flashy as Knock Out’s -- literally, as the red mech had installed light piping on his own at some point -- but it more than made up for that in impressive size and girth… and in a row of plates on either side that flared out even as he watched.

“Oh my… you’re a big fellow, aren’t you?” Mettaton chuckled, not taking his eyes from Breakdown’s equipment. “Those won’t hurt, will they?”

Breakdown chuckled. “They’re to increase pleasure for a partner. I won’t do too much with ‘em, since you’re not used to it, but maybe later.” 

“I’m sure he’ll get a chance to experience your magic soon, dear Breaky.” Knock Out knelt before Mettaton, combing the fingers of one hand through his hair. “We have all night to play, after all.”

Mettaton gave a groan of anticipation… one that quickly rose to a whimper of pleasure as Breakdown thumbed his panel open, one large but careful finger probing inside his valve. He bit his lip and bucked against the invading digit, craving more. Gods, he could have overloaded just from being handled like this.

“Primus, you’re hot.” He swirled the digit inside Mettaton’s valve, wrenching an impassioned cry from his vocalizer. “Heh… you look hot, yeah, but you feel hot inside, too. An’ your valve feels real nice.” He withdrew the finger and rested his hands on Mettaton’s hips. “I’m goin’ in… I’ll fit, it feels like, but it’s gonna be tight. Just to warn ya.”

Mettaton nodded. “Darling… less talk… more action… all right?” He could barely get the words out, he was venting so hard. Stars and crystals, he hadn’t been this turned on since… well, since his very first encounter with Knock Out, come to think of it...

He had no more time to ponder on that -- Breakdown was going in, the tip of his spike pressing into his valve and sliding deeper. He tossed his head, groaning, as the calipers in his valve clenched and rippled around the thick shaft, welcoming him, urging him deeper. Gods, he’d never had a shaft this big before… it stretched him deliciously, giving him a heady feeling of fullness that wasn’t by any means uncomfortable or painful…

“Oh Primus,” Breakdown gasped, gripping him by the hips. “You ARE tight… slag, Knock Out, I don’t think he’s gonna let me pull out.”

Knock Out laughed as he cradled Mettaton’s face in his hands. “Isn’t it delightful? Don’t worry, Breaky, just enjoy it. Now… let’s see if his mouth is as good as his valve, shall we?”

Mettaton tried to gather his wits enough to make a clever reply, but Breakdown chose that moment to shift his hips, thrusting once into his valve. A little cry wrenched from his vocalizer instead as pleasure stabbed through him, tingling throughout his wiring, making his soul blaze so brightly it was as if Alphys had installed a spotlight in his abdomen.

“Mmmm… Breakdown does good work, doesn’t he?” Knock Out patted his hip, and as if on cue his own spike -- smaller, sleeker, but beautiful with its crimson light piping and ribbed texture along the sides -- slid free. “About that mouth…”

Mettaton gave a little growl of lust and wrapped his fingers around the base of the spike, dragging his glossa up and down the metallic shaft. Knock Out’s look of smug satisfaction vanished as he threw his head back, exposing a throat just begging to be kissed and nibbled. His mouth formed an O of shock and ecstasy, and his own engine gave a roar of pleasure -- not the deep growl of Breakdown’s engine, but something higher and somehow wilder.

They really did make the most delightful noises, he thought as he continued to explore the red mech’s spike. Not just with their mouths, either.

Breakdown grunted softly. “That’s hot… slag, Metta, I wanna feel that mouth sometime tonight.”

“Mmm, you’ll get your turn,” Mettaton promised, and he wrapped his mouth around Knock Out’s spike. The roar of his engine became a scream, one echoes by a delightful cry from his vocalizer. Knock Out clenched his fists in the entertainment bot’s hair, hips thrusting ever so lightly into his mouth, frame trembling with pleasure and desire.

“Oh… my Primus…” Breakdown groaned and began to thrust as well, his hips pumping gently but powerfully against Mettaton, his spike withdrawing and plunging back in with carefully measured strokes. Gods, he was good at this… his movements just strong enough to let Mettaton feel the strength and power behind each thrust, but gentle enough to avoid doing damage. Small wonder Knock Out took him as a lover -- he was fantastic at this.

Knock Out cried out again as Mettaton worked his spike as well, matching his movements with Breakdown’s, letting lips and tongue work their magic. One hand remained fisted in Mettaton’s hair, the other reaching down to grip his shoulder as their combined movements sped up a notch, their combined pleasure climbing rapidly until Mettaton was sure one or more of them was going to explode from it.

Breakdown leaned forward abruptly to catch Knock Out’s mouth with his, never once breaking his rhythm. The scarlet mech whimpered softly in his lover’s mouth, surrendering to the kiss even as he trembled under Mettaton’s attentions. Mettaton, for his part, felt a new sort of desire burning in his core at watching the two of them, of seeing them share a moment of intimacy even in the heat of a most unlikely menage a trois.

 _I want that,_ he thought suddenly, through the haze of ecstasy that clouded his CPU. _I want that kind of passion… that pleasure beyond mere physical delight… that bond that can drive one to chase another through a barrier and into a treacherous Underground…_

Knock Out broke the kiss and arched his back, screaming as his chassis shuddered in the throes of climax. Mettaton clamped his mouth tightly around his spike, swallowing the flood of transfluid and priding himself in not letting a great amount of it escape. It was amazing, really, how compatible and similar their systems were…

He was next to overload, and he let his own cry rip through the suite as his valve clamped tightly around Breakdown’s spike. His own fluids ended up streaking his plating, and dimly he thought that it was a shame that he’d just polished not too long ago. The pleasure swamping his entire frame was so worth it, though…

Breakdown gave a roar to match the thunder of his engine as, with a final thrust, he overloaded deep inside Mettaton’s valve. He gasped at the hot wash of fluid filling his most sensitive areas, welcoming each thrust as the blue mech rode out his orgasm. 

When it was all over, Mettaton found himself nestled between the two of them on the fur rug, his face tucked into the crook of Knock Out’s neck, his back and aft pressed up against Breakdown’s chest and abdomen. The blue mech held his hands loosely at Mettaton’s waist while Knock Out stroked the black-and-magenta mech’s hair, a gentle smile on his face. He felt drained, exhausted, yet still tingling with pleasure at their coupling… and at the moment, there was nowhere else he wanted to be, either in the Underworld or on the surface.

“You really are an incredible find, dear,” Knock Out murmured. “It’s a pity we can’t take you with us when we go.”

“And it’s a pity you two can’t stay down here,” Mettaton replied, kissing his throat gently. “You’re wasted as soldiers -- you’d be fine additions to my show.”

Breakdown chuckled and patted Mettaton’s hip lightly. “I ain’t much of an actor, Metta. But still sounds better than a war, really.”

“It does, doesn’t it?” Knock Out hummed thoughtfully as he continued to smooth his hair back. “Breakdown… what are the odds of Megatron finding us down here? Or the Autobots?”

Breakdown shrugged. “Not that good. Megs doesn’t seem too keen on hunting us down, and the Autobots haven’t found anything on this mountain worth fighting over. Why?”

“Because I think we may be seeing a career change in the near future.” He chuckled and smiled as Mettaton gave him a look of wonder. “Oh darling, do you really think we would just ‘face you and run? You’re far more pleasant company than the brutes we normally associate with, and you’re one of the few beings in existence who’s nearly as beautiful as I am. And now that Breakdown’s taken a liking to you too… well, it would be a tragedy to leave you.”

Mettaton gave a happy laugh and kissed first Knock Out, then Breakdown. “This is splendid! I shall have to revamp my show immediately to accommodate two more special guests! You are, of course, welcome to occupy this suite as long as you’d like, unless you would rather I built you a new home somewhere in Hotland…”

“I dunno what he’s rambling about,” Breakdown laughed, “but it all sounds good to me.” He nuzzled Mettaton’s hair. “I need a bit to rest… then let’s see if we can’t get going again.”

“That sounds absolutely delightful,” purred Knock Out. “There’s so much more I want to try with you, dear.”

Mettaton smiled in anticipation. Having these mechs to himself for a good long while was enough to put him in an excellent mood. And perhaps, if they stayed here long enough, there would be a chance for their trysts to become something more…

Well, no sense counting his snowdrakes before they were hatched, he supposed. Still, the prospect of having two new co-hosts for his show -- as well as two new lovers with a fine appreciation for a robotic partner -- was enough to satisfy him for now. And it made him wonder if, perhaps, this was an opportunity for his entertainment empire to branch out into more -- ahem -- adult entertainment. There had to be a market for that in the Underground, right?

***

Toriel made it a habit to check a certain cavern every day to see if any humans had fallen down, but had gotten used to arriving there to find nothing. So it came as a shock to find, for the third time in a matter of months, a creature of metal sprawled in the golden flowers. Well now… the surface world must be populated by creatures of steel instead of humans now! That thought saddened her a little, but she pushed it aside and approached the creature. 

The silver-and-gray Cybertronian climbed to their feet, grumbling. She paused to take them in -- were they male or female? The frame was certainly feminine in build, with a sleek and slender body accentuated by sharply angled wings and with feet built to resemble high-heeled shoes, but the throaty rasp of a voice was most definitely masculine. Perhaps genderfluid -- there were certainly monsters in the Underground that didn’t adhere to traditional gender molds…

The mech made a swipe at the golden flowers at his feet, hissing out something that must have been an expletive, before turning to face Toriel. His crimson optics narrowed, and his lip curled in a sneer.

“What are YOU?” he demanded. “When did these squishy insects grow so big? And start sprouting fur? Disgusting!”

She decided it would be impolite to correct him and insist she wasn’t an insect. “Greetings, stranger. I am Toriel, caretaker of the Ruins. I check this cavern every day to see if anyone has fallen down. May I have your name?”

The mech cocked an eyebrow-like piece of metal as he stared at her. “You speak.”

“Yes, I do. And I just asked you your name, stranger. Could you give it to me, please?” She folded her hands before her, patiently awaiting an answer.

He regarded her a moment longer, then offered up an answer. “Starscream.”

“Greetings, Starscream. Come with me. I will guide you through the Ruins, and perhaps I can help you reunite with your friends. I’m sure they’ll be ecstatic to see you…”

**Author's Note:**

> Yes, leaving this one wide open for a possible sequel. Mettaton's going to end up with a freaking harem by the time this is all over...


End file.
